Identification of Coulomb blockade and macroscopic quantum tunneling by noise
Fakultät für Physik, Albert-Ludwigs-Universität -
Hermann-Herder-Straße 3 D-79104 Freiburg, Germany
2 Institut für Physik, Universität Augsburg - Universitätsstraße 1 D-86135 Augsburg, Germany
Accepted: 14 February 2002
The effects of Macroscopic Quantum Tunneling (MQT) and Coulomb Blockade (CB) in Josephson junctions are of considerable significance both for the manifestations of quantum mechanics on the macroscopic scale and potential technological applications. These two complementary effects are shown to be clearly distinguishable from the associated noise spectra. The current noise is determined exactly and a rather sharp crossover between flux noise in the MQT and charge noise in the CB regions is found as the applied voltage is changed. Related results hold for the voltage noise in current-biased junctions.
PACS: 74.50.+r – Proximity effects, weak links, tunneling phenomena, and Josephson effects / 74.40.+k – Fluctuations (noise, chaos, nonequilibrium superconductivity, localization, etc.) / 73.23.Hk – Coulomb blockade; single-electron tunneling
© EDP Sciences, 2002